High performance disc drives achieve a real bit densities in the range of several gigabits per square centimeter (Gbits/cm2). Higher recording densities can be achieved by increasing the number of bits per centimeter stored along each information track, and/or by increasing the number of tracks per centimeter written across each recording surface. Capacity increases gained through increasing the bits per centimeter stored on each track generally require improvements in the read/write channel electronics to enable data to be written to and subsequently read from the recording surface at a correspondingly higher frequency.
As density increases through increased bits per centimeter along the information track, controlling a fly height of the read/write head relative to the information track becomes more demanding. The ability to control the fly height of the read/write head relative to the information track through the mechanical configuration of the disc drive can no longer be depended on to produce disc drives while maintaining high yields in the manufacturing process.
Additionally, as the Read/Write transducer becomes more and more sensitive to electrical overstress, methods to protect the transducer have been implemented. Some of these methods employ an electrically removable resistive shunt (ERS) across the read transducer. The shunt is electrically removed at some stage in the manufacturing process. shunt (ERS) across the read transducer. The shunt is electrically removed at some stage in the manufacturing process.
Therefore challenges remain and needs persist for means of measuring the fly height of the read/write head within an assembled disc drive, referred to as an “in-situ” operation, absent the external measurement equipment to provide a basis for fly height control of the read/write head in a disc drive. In addition, a method to verify the complete removal of the shunt is needed.